Magnesium (Mg) is the second-most abundant intracellular cation and, overall, the fourth-most abundant cation. Almost all enzymatic processes using phosphorus as an energy source require magnesium for activation. Magnesium is involved in nearly every aspect of biochemical metabolism (eg, DNA and protein synthesis, glycolysis, oxidative phosphorylation). Almost all enzymes involved in phosphorus reactions (eg, adenosine triphosphatase [ATPase]) require magnesium for activation. Magnesium serves as a molecular stabilizer of RNA, DNA, and ribosomes. Because magnesium is bound to ATP inside the cell, shifts in intracellular magnesium concentration may help regulate cellular bioenergetics such as mitochondrial respiration.
The total body content of magnesium in adults is about 2,000 mEq or 24 g. Approximately 60% of total body magnesium is located in bone and the remainder is in the soft tissues. Serum concentration of magnesium typically ranges from 1.8-2.5 mEq/L. Approximately a third of this is protein-bound. The free (i.e. unbound) fraction of magnesium is considered as the active component.
Magnesium is primarily absorbed in the small intestine at a rate depending on the dietary intake, in the healthy individual. Absorption occurs primarily in the jejunum and ileum via ionic diffusion (passive) and at low luminal concentrations through active transport processes. The sigmoid colon also has some capacity for magnesium absorption. A minimal daily intake of 0.3 mEq/kg of body weight has been suggested to prevent deficiency. Infants and children tend to have higher daily requirements than adults.
The kidney is the major excretory organ for absorbed Mg. The average excretion of Mg in urine per day usually varies between 2 and 5 mmol.
Magnesium deficiency and hypomagnesemia are often asymptomatic. However, severe symptomatic hypomagnesemia may manifest clinically as tetany and generalized seizures. Early manifestations may include muscle cramps, nausea, vomiting, and lethargy.
Although no comprehensive studies have addressed the actual incidence of hypomagnesemia stratified by age group, neonates, in particular preterm infants are more predisposed to develop hypomagnesemia. As a matter of facts, prematurity is considered to be one of the major risk factors for Mg deficiency (Caddell J L. Magnesium in perinatal care and infant health. Magnes Trace Elem 1991; 10(2-4):229-50). Key reasons for the high risk of deficiency in preterm infants are the limited magnesium stores in the body and the high requirement for bone and intracellular magnesium inherent to the accelerated growth rate in these infants. Magnesium deficiency can increase the risk of severe neonatal complications such as intracranial haemorrhage, periventricular leukomalacia or bronchopulmonary dysplasia, as well as of life-long sequelae such as cerebral palsy and chronic lung disease (Caddell J L, Graziani L J, Wiswell T E et al. The possible role of magnesium in protection of premature infants from neurological syndromes and visual impairments and a review of survival of magnesium-exposed premature infants. Magnes Res 1999; 12(3):201-16; Caddell J L. Evidence for magnesium deficiency in the pathogenesis of bronchopulmonary dysplasia (BPD). Magnes Res 1996; 9(3):205-16.)
Thus, there is a need for a nutritional composition for use in the promotion of magnesium absorption and/or magnesium retention, in particular in infants and young children, preferably infants, who were born preterm or with low-birth weight (LBW) or experienced intra-uterine growth retardation (IUGR) or suffer from malabsorption, chronic diarrhea, short bowel syndrome and/or from growth stunting because of malnutrition, such as suboptimal intra-uterine nutrition, and/or disease.
Oligosaccharides, especially fructo-oligosaccharides and inulin, are known to promote magnesium absorption and/or retention in a dose-depended manner. Medium to high doses equivalent to more than 5% of dietary intake of oligosaccharides are often required to observe a positive effect. However, the gastrointestinal tolerance of these medium to high doses is often poor, and lead to abdominal distension and pain, flatulence and in some cases diarrhea. Therefore, there is a need for a new nutritional composition that can promote magnesium absorption and/or magnesium retention, at a low dose, compatible with the absence of gastrointestinal symptoms and with a good digestive tolerance. There is more generally a need for this nutritional intervention in young mammals, in particular infants and children, preferably infants, but also young pets.
There is a need for such intervention that induces the maintenance of an adequate magnesium level, by means of promoting absorption and/or retention, in humans and in animals, especially in young mammals.